n = input()

wl = [int(x) for x in input().split()]

if sum(wl) % 2 == 1:
    print("impossible")
else:

    obj_sum = sum(wl) // 2
    
    x = True
    tmp = [[[], 0]]
    cnt = 0

    while x and cnt < len(wl) - 1:
        new_tmp = []

        for t in tmp:
            for i in range(len(wl)):
                if i not in t[0]:
                    new_tmp.append([t[0].append(i), t[1] + wl[i]])
        
        for i in new_tmp:
            if i[1] == obj_sum:
                x = False
                break

        cnt += 1
        tmp = new_tmp

    if x:
        print("impossible")
    else:
        print("possible")